The present invention generally relates to communications systems and, more particularly, to wireless systems, e.g., terrestrial broadcast, cellular, Wireless-Fidelity (Wi-Fi), satellite, etc.
Today, the number of communication signals being broadcast is on the rise. In addition, these broadcast communication signals may use different types of modulation. One form of receiver that supports multiple modulation types is represented by the currently proposed Chinese Digital Television System (GB) 20600-2006 that specifies a receiver support a single carrier (SC) modulation mode and a orthogonal frequency division multiplexing (OFDM) modulation mode. This receiver determines the type of modulation in the received signal by setting itself to each type of modulation until the receiver correctly recovers data in the received signal. For example, the receiver may first configure itself to receive an OFDM signal, and then test for the presence of predefined data in the received signal. If this test succeeds, the receiver assumes that the received signal is an OFDM signal. However, if this test should fail, then the receiver configures itself to receive a single carrier signal and then, again, tests for the presence of the predefined data in the received signal. Unfortunately, the presence of multipath effects may make it difficult for the receiver to locate the predefined data—whatever modulation type the receiver is set to. As a result, the receiver may take a long time to correctly determine the modulation type since the receiver will continue to switch back and forth between modulation types searching for the predefined data.